One of the nicest things you could to do Jeppe Carlsen, who helped design Limbo's puzzles, is tell him you want to slap him in the face.
The stark aesthetics of 2d platformer Limbo earned it an award for visual arts at the Game Developers Choice Awards, but it was the game's delightfully cruel puzzles that won it so many devoted fans. Carlsen, who had no design experience joining Playdead, was lead gameplay designer for Limbo and "basically if [you] got stuck in the game, I'm the guy you wanted to slap in the face."
Speaking at GDC, Carlsen explained that Playdead had a very simple goal for Limbo: Make it about challenging problem solving. Giving the player genuinely difficult challenges to overcome sounds like an obvious aspect of game design, but Carlsen said he feels it's something most triple-A titles lack. Games like Uncharted 2 might give you tasks that feel like a puzzle - such as aligning a bunch of mirrors to guide a beam of light to a specific spot - but those aren't really puzzles because when you're done, you don't have the satisfaction of having figured something out. You've completed a task, perhaps even one that required a certain amount of dexterity or skill, but you didn't really need to tax your brain.
That may be fine for Uncharted, which emphasizes story and action over problem solving, but that wasn't good enough for the designers at Playdead, who spent 3 years brainstorming puzzles for Limbo. They wanted to give players problems that would really force them to think. For a puzzle to make the cut and be worthy of inclusion in Limbo, it had to have the right balance of frustration and simplicity.
"When we design puzzles," he said, "we want to make sure the elements and the mechanics in the puzzle are very simple." The challenge shouldn't lie in figuring out what you have, but rather what you can do with what you have. Similarly, each puzzle should also have as few elements as possible. If there are too many options and pieces, the player is less likely to actually sit down and try to work it out, and more likely just force their way through it with trial and error. Adding a bunch of different elements might make a puzzle more difficult, says Carlsen, but it probably won't make it more fun.
To illustrate his point, Carlsen demonstrated a puzzle from Chapter 16 of Limbo, which you can see at 1:43 in the video. It has just three elements: the switch panel, the chain, and the electrified floor. Because there's so little here, it takes no time at all for you to realize your goal: Use the chain to get across the floor. Now you just have to figure out how.
If the Playdead team has designed the puzzle well, your early experiments with the switch, the chain, and the floor, will result in your death. "When you come into a puzzle, you don't know anything about it, so you just sort of start messing around with things. I don't want you to solve the puzzle by using intuition and performing simple experiments. I want you to die, I want you to be frustrated. I want you to come up with different possible solution strategies. You should learn by dying," said Carlsen.
"The player is my enemy. I try to come up with the most evil, devious tricks I can," Carlsen continued, explaining that he will try to predict the player's likely behavior, then require the opposite. For the chain puzzle, the first thing the player sees is the switch, which they will most likely immediately push, then make a dash for the now-moving chain, which they cannot possibly catch. In other words, they will die. Just like Carlsen wants them to.
But only for a while. Sure, he wants you to fail, but only because it will make your eventual victory that much more fulfilling. "The player is also my friend. We try to put these tricks in the most accessible environment we can. The rewarding feeling you get [from solving the puzzle] is so much stronger if you had to struggle."
If you got so crazy that you actually wanted to smack him in the gob,well, that would just plain make his day.